In U.S. Pat. No. 5, 411,466, R. L. Hess discloses a balloon angioplasty catheter having "an angioplasty balloon with dose means in the form of radioactive elements attached thereto." In U.S. Pat. No. 5,484,384, N. E. Fearnot discloses a balloon filled with a radioactive fluid that "is injected into the balloon for irradiating the treatment site."
One problem with the Hess invention is that separate radioactive elements on the outside of an angioplasty balloon can become detached, particularly when the balloon expands, which can result in distal emboli that can block a downstream artery. Also patches on the balloon's exterior surface could leach out radioactive matter into the blood stream which is undesirable. Still further, patches on the balloon's exterior surface do not provide uniform irradiation of the tissue of the arterial wall which again is undesirable.
Placing a radioactive liquid into a balloon is highly undesirable because the balloon angioplasty catheter can leak or break and release the radioactive fluid into the blood stream. Furthermore, a radioactive fluid leak can occur where the fluid is injected at the proximal end of the balloon catheter.